Extra "wrong way" and "do not enter" signs were placed on exit ramps along the Dallas North Tollway.

"There has been a lot of attention drawn to this, and we think we need to make a statement to the region that this is important," said Allen Clemson, NTTA executive director.

Since April, four people have died in four wrong-way crashes on the Dallas North Tollway.

Maintenance crews are also gluing reflective pavement markers on all of the tollway's 47 exit ramps during the next two weeks. The raised and reflective pavement markers are used to direct exiting vehicles with a white arrow that will reflect red when drivers try to enter the wrong way.

"We're very sympathetic and very concerned over the tragedies that have happened," Clemson said. "We want to go a little bit further to make that extra effort to make sure people feel comfortable driving our roads."